Rinse the aged kimchi sheets well under running water and squeeze out the water firmly.
In a mixing bowl, lightly season the rinsed kimchi with perilla oil and sugar.Note: If the kimchi is very sour, you may add a little more sugar.
Prepare the Tuna Mayo
Squeeze the oil out of the canned tuna very well. Combine the drained tuna with mayonnaise in a mixing bowl and mix thoroughly.
Season the Rice
Season the warm cooked rice with salt and perilla oil. Mix gently, ensuring the seasoning is even.Note:Since the kimchi is already salty, do not over salt the rice.
Assemble and Roll
Lay seasoned mukeunji flat.
Spread a layer of seasoned rice evenly over the mukeunji. Place a line of the Tuna Mayo mixture.
Roll the mukeunji(aged kimchi) tightly, similar to rolling kimbap.
Garnish
Finely chop only the green part of the green onion for garnish.
Brush the finished mukeunji rolls with the perilla oil.
Slice the rolls into bite sized pieces. Top the rolls with the chopped green onion and toasted sesame seeds.